Seats of this type are known in a large number of different configurations. The sitting surface frame and the backrest frame of the seat frame may differ in their upholstery. Such known seats are adjustable in terms of their seat contour and backrest contour, but are generally not sufficiently adapted to the ergonomics of a user, meaning that comfort is accordingly restricted and the user's back is not adequately supported by the backrest frame in each position, which can sometimes lead to back complaints.
A vehicle seat is thus known from, for example, DE 4405397 C1, of which the backrest frame is subdivided into a plurality of subsegments which are pivotable with respect to one another about a vertical axis of rotation.
A vehicle seat fitted with a backrest frame which is movable in this manner does make it possible to improve access for users to actuation members behind the seat and, by means of the user's upper body rotating with respect to the centre of the vehicle, to achieve simpler passage in a two-door motor vehicle, even for back-seat passengers, without obliging those sitting at the front to vacate the vehicle.
However, this movable backrest frame is not optimally adapted to human ergonomics so that the user of such a vehicle seat may therefore in some circumstances not experience the required seating comfort but rather may even have to put up with back complaints owing to the use of such a vehicle seat.